Adaptive semi-soft handoff for cellular IP networks

Abstract:

Rapid advances in wireless networking have led to more mobile phones,
PDAs, and other digital mobile devices becoming ubiquitously connected to the
Internet. As the demand of delay sensitive real-time applications for these portable
devices increases, providing seamless connectivity to wireless networks becomes a
critical issue. For this reason, a number of micro-mobility protocols, such as
Cellular IP, have been proposed to complement the Mobile IP protocol. However,
providing fast and reliable handoff is still a major obstacle to enabling seamless
micro-mobility in wireless access networks.
Cellular IP semi-soft handoff has been proposed to address such challenge.
Evaluations have been performed which show that semi-soft handoff yields better
performance than the conventional hard handoff. However, these studies are based
on symmetrical network topologies and loads. In practice, network topology varies and the network load fluctuates depending on numerous parameters (e.g., number
of mobile nodes, amount of traffic in the network, etc.). Semi-soft handoff uses
fixed delay device and semi-soft delay values for stream synchronization and
mobile host’s tune-in timing. Such scheme may work well for the evaluated
symmetrical setup. However, this will not be the case with unbalanced and
dynamically changing networks, as what are typically found in real life.
This paper describes a novel adaptive protocol (Adaptive-SS), which is
proposed as an extension to the current Cellular IP semi-soft handoff protocol to
address such issue by assigning delay device and semi-soft delay values
dynamically based on the present network condition. The simulation results show
that Adaptive-SS significantly reduces network traffic and packet losses and
duplications during handoff, while still minimizing handoff latency.